Toxicologist Ian Eiloart of the "crsociety" newslist claims that raw
kidney beans are toxic; as few as a dozen could kill you, says he. When
I threatened to eat some, he sent me the following info. Do any of you
guys know anything about this? Is it real or is it Memorex?
Bob Avery ([log in to unmask])
--------- Begin forwarded message ----------
From: Ian Eiloart <[log in to unmask]>
Note the assumption of toxicity. These people are trying to find out how
the toxin works. A quick search of the database reveals at least 40 more
studies with the words 'lectin' and 'kidney bean'.
[log in to unmask] wrote:
>
> Copyright 1996, Institute for Scientific Information Inc.
>
> Database: Science Citation Index
>
> (1) TI: TRANSPORT OF TOXIC KIDNEY BEAN (PHASEOLUS-VULGARIS) LECTINS
> INTO THE VACUOLAR SYSTEM OF INTESTINAL EPITHELIAL-CELLS OF
RATS
> AU: KING_TP, PUSZTAI_A
> NA: ROWETT RES INST,BUCKSBURN AB2 9SB,ABERDEEN,SCOTLAND
> JN: BIOLOGY OF THE CELL, 1982, Vol.45, No.NSI, p.217
> DT: Meeting Abstract
>
> (2) TI: EFFECT OF KIDNEY BEAN (PHASEOLUS-VULGARIS) TOXIN ON TISSUE
> WEIGHT AND COMPOSITION AND SOME METABOLIC FUNCTIONS OF RATS
> AU: GREER_F, BREWER_AC, PUSZTAI_A
> NA: ROWETT RES INST,BUCKSBURN AB2 9SB,ABERDEEN,SCOTLAND
> JN: BRITISH JOURNAL OF NUTRITION, 1985, Vol.54, No.1, pp.95-103
>
> (3) TI: STABILITY OF RED KIDNEY BEAN LECTIN
> AU: COFFEY_DG, UEBERSAX_MA, HOSFIELD_GL, BENNINK_MR
> NA: MICHIGAN STATE UNIV,DEPT FOOD SCI & HUMAN NUTR,E
> LANSING,MI,48824
> DOW CHEM CO USA,MIDLAND,MI,48674
> MICHIGAN STATE UNIV,DEPT CROP & SOIL SCI,E LANSING,MI,48824
> JN: JOURNAL OF FOOD BIOCHEMISTRY, 1992, Vol.16, No.1, pp.43-57
> IS: 0145-8884
> AB: Lectins are toxic heat-stable glycoproteins, termed
-------------------------------
> phytohemagglutinins, that depress the nutritional quality of
> Phaseolus vulgaris. Purified phytohemagglutinin (PHA-P) was
> separated from dark red kidney beans (Montcalm cultivar) by
> affinity chromatography and subjected to various treatments
> including: thermal (70-100C, chemical (2 M NaCl, 5 M urea, 5
% mercaptoethanol, pH 12 and pH 3) and enzymatic (peptidases,
> proteases and carbohydrases). At 70C, the PHA-P activity
decreased with a linear response. Exposure to pH 12 or 5 M
urea were the most effective chemical treatments for reducing
> hemagglutinating activity. Treatment with proteases resulted
in 88-98% reductions in PHA-P activity. Mannosidase treatment
> resulted in a slight but significant (P < 0.01) reduction in
> activity; however, amylases and neuraminidase had no effect
on activity. Terminal sialic acid residues may not be an
important determinant of PHA-P activity.
> KP: PHASEOLUS-VULGARIS LECTIN, RAT SMALL-INTESTINE, INDUCED
LESIONS, HEMAGGLUTINATING ACTIVITY, PROTEIN DIGESTIBILITY, THERMAL
> INACTIVATION, TOXICITY, ISOLECTINS
>
Of course, 'heat-stable' is a relative term. So, this says cook them and
cook them well. The usual recommendation is to cook them on a rolling
boil for 15 minutes at least , after soaking them properly.
> (4) TI: EFFECT OF PHASEOLUS-VULGARIS LECTINS ON GLUCOSE-ABSORPTION,
> TRANSPORT, AND METABOLISM IN RAT EVERTED INTESTINAL SACS
> AU: SANTIAGO_JG, LEVYBENSHIMOL_A, CARMONA_A
> NA: CENT UNIV VENEZUELA,ESCUELA BIOL,CTR BIOL CELULAR,APARTADO
> POSTAL 47069,CARACAS,VENEZUELA
> JN: JOURNAL OF NUTRITIONAL BIOCHEMISTRY, 1993, Vol.4, No.7,
pp.426- 430 IS: 0955-2863
> AB: Many legume seeds contain lectins. Some of these lectins are
> toxic when fed to humans or laboratory animals. Although the
> mechanism for such toxicity has not been clearly elucidated,
> lectin binding to the intestinal mucosa is an obligatory
step. Therefore, the interaction of lectin and enterocytes may
> interfere with the digestive process. Lectins from toxic (red
> kidney bean) and non-toxic (mountaineer half runner)
Phaseolus vulgaris varieties were tested for their effect on the
> intestinal absorption, transport, and metabolism of glucose.
> Both lectins were purified by affinity chromatography on Con
A-Sepharose 4B. Everted sacs, 5 cm long, from the first third
of the small intestine were incubated for 20 min in the presence
> of 10 mmol/L glucose in both the luminal and serosal media.
> Pre-incubation (15 min) of the everted sacs with increasing
> concentrations of the red kidney bean lectin (50-200 mug/mL
> mucosal solution) before glucose addition reduced both the
> absorption and transport of the sugar from the luminal to the
> serosal side. Glucose metabolism as judged by lactate
formation was not affected. At a concentration of 100 mug/mL of red
> kidney bean lectin, absorption, and transport were inhibited
by 40% and 72%, respectively. Lactate production was decreased
by only 5%. Under the same conditions (100 mug/mL) mountaineer
> half runner lectin inhibited glucose absorption and transport
> by less than 10%. Interference of lectins with the absorption
> and transport of nutrients could partially explain the toxic
> effect of lectins from some Phaseolus vulgaris varieties.
> KP: D-GALACTOSE, L-LEUCINE, TOXICITY, BINDING, DIGESTIBILITY,
> LOCALIZATION, PROTEINS, INVITRO, DIET
> WA: PHASEOLUS-VULGARIS, LECTINS, INTESTINE, GLUCOSE TRANSPORT
>
> (5) TI: DIGESTIBLE AMINO-ACIDS FOR NON-RUMINANT ANIMALS - THEORY AND
> RECENT CHALLENGES
> AU: WILLIAMS_PEV
> NA: RHONE POULENC ANIM NUTR,42 AVE ARISTIDE BRIAND,BP 100,F-92164
> ANTONY,FRANCE
> JN: ANIMAL FEED SCIENCE AND TECHNOLOGY, 1995, Vol.53, No.2,
pp.173-187 IS: 0377-8401
> AB: Accurate assessment of amino acid requirements of livestock
formaintenance and growth and accurate supply of these amino
acids in feed is essential to optimise growth and production.
During passage through the gut and during absorption, the
composition of dietary supplied amino acids is modified compared with
that absorbed into the portal circulation. Amino acids are
utilised for endogenous secretion and protein synthesis in gut tissue
> nd transamination occurs within the gut tissues. In pigs,
each amino acid has its own characteristic of appearance in the
> portal vein which varies according to the amount of ingested
> protein. When small rather than larger amounts of amino acids
> are ingested, the absorbed mixture tends to be poorer in
> lysine, arginine, serine and proline and richer in histidine.
> Factors which influence the metabolism of gut tissue may
enter the quantity and composition of amino acids absorbed. The gut
> micro-flora increases protein synthesis in gut tissue; in
> conventional compared with germ free chicks protein synthesis
> in gut and liver was increased by 36%. Raw kidney bean
lectins produce hyperplasia in gut tissue, and the toxic effect is
considerably increased by the presence of a normal gut
microbial population. In-feed antibiotics appear to act at
-least at two levels, either via a nutrient sparing effect,
with improvements in digestibility and/or enhanced absorption of
> amino acids plus a reduction in cell turn-over at the surface
> of the enterocyte. Hind-gut microbial fermentation influences
> amino acid digestibility. The lower the digestibility of the
> protein supplement the more microbial fermentation affects
> digestibility. Total tract digestibility is therefore not a
> good estimate of the amino acids absorbed in the small
> intestine. In intact compared with caecectomized cockerels
> there was little difference between faecal and ileal
> digestibility of amino acids for cereals, slight differences
> for oilseed meals, but significant differences for some
animal meals. Lysine digestibility of meat and bone meal in intact
and caecetomized birds was 0.88 and 0.82 respectively in meal
> without heat treatment and 0.58 and 0.45 respectively in heat
> treated meal. With diets for growing pigs in which meat and
> bone meal or cottonseed meal partially replaced soya bean
meal, formulations based on ileal digestible amino acids produced
> better performance than those formulated on the basis of
total amino acids. Ileal digestibility values are appropriate for
> estimation of amino acid digestibility of cereals as they
> account for losses in digestibility but in heat damaged meat
> meals differences exist between ileal digestibility and
> availability of lysine, methionine, threonine and tryptophan.
> Correlations between in vitro methods and in vivo ileal
> digestibility are quite close although in vitro values tend
to be higher; inclusion of the association between amino acids
an cell wall carbohydrates raises the variation explained
between samples in ileal protein and amino acid digestibility to >
92%. Near-infrared reflectance spectrophotometry holds promise as
a tool for predicting ileal digestibility. Use of ileal
> digestibility values in diet formulation increases the range
of ingredients that can be employed, improves the accuracy of
> formulation and prediction of animal performance. Ileal
> digestibility measurements represent a good compromise
between the requirement for a rapid, economical determination of the
> digestibility of amino acids in feed and the measurement of
> availability of amino acids for tissue synthesis.
> KP: PROMOTING FEED ADDITIVES, NITROGEN-METABOLISM, PROTEIN-
> SYNTHESIS, GUT MICROFLORA, PIGS, POULTRY, MEALS, FLORA, DIET
> WA: DIGESTIBLE AMINO ACIDS, NON RUMINANTS, PIGS, POULTRY
>
> **** End of Data ****
cheers, Ian Eiloart
<http://www.cogs.susx.ac.uk/users/iane>
<http://www.cogs.susx.ac.uk/users/iane/coops>
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